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Discussion Starter · #1 ·
what is the name of the tube coming off the exhaust manifold? I need to replace it but don't know what it's called. It's not the EGR tube that goes across the engine to the EGR valve, I talking about the other tube on the outside
 

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What he said. Connects to the aircleaner to provide heated air off the exhaust to warm the engine up faster. When cold, engine vacuum open a flapper that allows the warm air off the exhaust to flow into the aircleaner. As the engine warms up (so does the bypass valve) it shuts off the vacuum and the flapper closes.

Since it's part of the emissions system, I failed smog test one year only because that tube was missing. I was able to replace it with some flex tubing from a nearby Volkswagen speed shop (the old Beetles used these).

You didn't saw what year/model/engine you have so here's my D21 2.4. The red lines indicate where the hot air tube would be (wasn't there when I took this pic). The gizmo in green is the bypass.

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What he said. Connects to the aircleaner to provide heated air off the exhaust to warm the engine up faster. When cold, engine vacuum open a flapper that allows the warm air off the exhaust to flow into the aircleaner. As the engine warms up (so does the bypass valve) it shuts off the vacuum and the flapper closes.

Since it's part of the emissions system, I failed smog test one year only because that tube was missing. I was able to replace it with some flex tubing from a nearby Volkswagen speed shop (the old Beetles used these).

You didn't saw what year/model/engine you have so here's my D21 2.4. The red lines indicate where the hot air tube would be (wasn't there when I took this pic). The gizmo in green is the bypass.

View attachment 10123
Clean little engine. So many of these trucks have changed hands that typically someone has started ripping stuff off, and then they wonder why it doesn't run right.
 

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Discussion Starter · #5 · (Edited)
@jp2code Yea, I know what you mean! I got the truck with an aftermarket intake and header and I don't have that intake valve...I forgot to mention I have a 1992 hardbody with the 2.4L engine.
In the pictures, the red arrow is the tube I'm talking about, and the blue arrow is the valve it connects to. After the valve, it looks like it terminates at a flat round expansion chamber.
I'm trying to replace that tube because I have an exhaust leak there where it connects to the header, and also because that tube contacts the AC lines and rattles when driving.
If I cap off this heater tube, will I get a CEL on? I have to do emissions where I live. Thanks for the info!
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Please, next time indicate if you're not running stock parts. What year is your D21.

If I had to guess, I'll guess it's the Air Induction Valve (A.I.V.) pipe. The blue gizmo is the valve. Does the other end go to the Cat?
 

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Discussion Starter · #12 · (Edited)
Standard Motor Products DH3 Pre-Heater Hose, Size 1-1/2 x 7 inches, Expandable to 20 inch Assorted https://a.co/d/8hInoup

That should work
I'm confused...please help me understand what you're saying
The metal tube (that the red arrow is pointing to in the pic) is maybe 3/4 inch, has a threaded collar that attaches the tube to the exhaust on one end, and on the other end of the tube it's attached to the valve (blue arrow)
The 1.5" heater hose you recommended is double the diameter and not threaded.
I'm just trying to picture how this would work: I crumple and crush the 1.5" heater hose down to fit around the 3/4" connector on the exhaust and also to the valve and then secure it with a hose clamp or something? Wouldn't that leak from the gaps where crushed down? I mean I already have an exhaust leak there, I'm trying to get rid of it...
If I can't get a OEM or after-market replacement tube I was thinking of using a 3/4" silicone tube with hose clamps to secure it. What do you think of that idea?

P.S. I'm a subscriber to your YouTube channel, I really enjoy your Nissan videos. My name on there is 3RAN7ON. On your latest "short" asking how to fix a crappy seatbelt, the answer is to retract it out all the way, get a bucket of dish soap and water. Soak the belt for a bit and then use a small brush to scrub out all the dirt from it you can. Once clean, dry it out as much as possible and then use silicone spray to put a light coating on both sides of the part of the belt that will wind into the retractor mechanism. Should work like brand new.
 

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The heater hose doesn't have to be air tight. A universal hose with a clamp will work to get the heat directed to where it is needed.... unless I misunderstood the picture. Mine is the V6, so things are setup different.

I'm going to investigate the seat belt cleaning idea. Your suggestion isn't the first time I've read that.
 

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what is the name of the tube coming off the exhaust manifold? I need to replace it but don't know what it's called. It's not the EGR tube that goes across the engine to the EGR valve, I talking about the other tube on the outside
It's just a way for the engine to tell when it's getting warm, so the "auto choke" feature turns off. I put "auto choke" in quotes because the engine doesn't really have a choke.



 
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